Begüm Horuluoglu

Background: Interstitial lung disease (ILD) is a common manifestation and the primary cause of mortality in patients with a chronic autoimmune systemic inflammatory disease called inflammatory myopathy or myositis. Up to 90% of the patients with anti-melanoma differentiation-associated gene 5 (MDA5) and anti- histidyl t-RNA synthetase (Jo1) develop signs of ILD. The course of ILD can be chronic or as in patients with anti-MDA5 autoantibodies it can be rapidly progressive with a high mortality. Current treatment is based on high doses of glucocorticoids in combination with immunosuppressive drugs, still interstitial lung disease is one of the main causes of morbidity and death in these patients. B cells and autoantibodies have been suggested to contribute to disease pathogenesis especially in anti-MDA5+ patients, based on clinical improvement in some patient upon treatment with B cell depleting or antibody removal therapies. However, we still lack the understanding of the function of these autoantibodies. Aim: We hypothesise that autoantibodies against MDA5 are pathogenic and contribute to disease pathogenesis in patients with interstitial lung disease (ILD). Thus, the main goal of this project is to understand the mechanisms leading to antibodies production, their target and function of at the tissues in patients with myositis associated ILD. Workplan: We will first study the auto-antibody reactivities in patients from different cohorts along with proteomics and luminex based antibody profliling assays to understand possible disease mechanisms. Next, we will study the B cells in peripheral blood of patients with and without ILD and characterize antigen specific B cells using multicolor flow cytometry. Single B cell receptor (BCR) sequencing will be done on antigen specific B cells. BCR sequences will be used us to produce human derived monoclonal antibodies. The target of the autoantibodies will be studied using spatial protemics. Functional assay will be done using peripheral blood cells and lung/muscle tissue derived cells or cell lines. Significance: ILD is the main cause of morbidity and mortality in patients with myositis. Removal of autoantibodies and depletion of B cells has been shown to be clinically effective in some patients, indicating their role in disease pathogenesis. However the functionality of autoantibodies in the ILD is not known. An improved understanding of the molecular pathways that drive the immune reaction leading to this

Myositis is a complex autoimmune disease with high morbidity and mortality. Biomarkers to predict prognosis are lacking. Newly discovered myositis specific autoantibodies predict distinct clinical phenotypes and are promising biomarkers to identify subgroups that may share molecular pathways and prognosis.In unique patient cohorts we aim to identify prognostic biomarkers in distinct sub-groups of myositis, defined by clinical features, autoantibody profile and genetics. We aim to identify antigen specific T and B cells and changes in muscle tissue that relate to changes in muscle strength after therapy. Immunological and molecular methods as well as proteomics and transcriptomics will be applied.Registry data will be used to predict treatment response. Functional, molecular studies will be focused on three sub-phenotypes of myositis patients

anti-Jo-1 positive with a high frequency of interstitial lung disease, anti-MDA5 positive with severe lung disease, anti-FHL1 positive, a muscle-specific antibody with profound muscle weakness. Mechanisms for generation of autoantibodies and immune specificity of T and B cells will be investigated in blood, muscle and bronchoalveolar lavage fluid. Effector function of T cells and antibodies will be investigated in cell cultures.Information on biomarkers for prognosis is highly needed to select right immunosuppressive treatment to the right patient and information on molecular pathways is important to develop new and specific therapies.